This invention is generally directed to toner and developer compositions, and more specifically the present invention is directed to toner compositions, including magnetic, single component, and colored toner compositions with polyethylenes. In one embodiment of the present invention, the toner compositions are comprised of polyester resin particles, reference U.S. Pat. No. 3,590,000, the disclosure of which is totally incorporated herein by reference, pigment particles, and certain crystalline polyethylenes, especially those with a weight average molecular weight of from about 500 to about 1,200, and preferably 1,000. Also, the present invention is directed to processes for providing low melt, from about 100.degree. C. to about 130.degree. C., roll fusible toners by adding thereto certain crystalline olefins, such as polyethylenes, and wherein the toner resin is comprised of a linear polyester. In one embodiment, there is incorporated into the linear polyester as a second incompatible phase an effective amount, for example from about 1 to about 10 weight percent, of the crystalline polyethylene. During roll fusing in an electrophotographic, especially a xerographic, imaging apparatus, such as the Xerox Corporation 5090.RTM., the molecular weight of the polyethylene can be selected to enable the melting thereof prior to any substantial fusing of the toner resin; thus, in this embodiment the polyethylene is in the liquid form prior to the melting of the toner resin, and it can migrate to the toner/fuser interface and provide fuser latitude for hot offsetting. Offsetting can occur when the toner particles are substantially retained, or are not fully released from the toner transporting means or roll; and fusing lattitude can be referred to as the temperature range between the minimum fix and hot offset toner temperature. Thus, for example, with the processes of the present invention the amount of fuser release oil selected can be reduced to, for example, 2 microliters per copy from 20 to about 50 microliters per copy. With the toners and processes of the present invention, the fuser temperature can be reduced by as much as 45.degree. C. while achieving an excellent latitude in embodiments thereof. The linear polyethylenes selected for the present invention preferably have a number average molecular weight of less than about 1,500 and melt below about 125.degree. C., which polyethylenes are available from Petrolite Corporation as, for example, POLYWAX 1,000.TM., POLYWAX 655.TM. and POLYWAX 500.TM. with a weight average molecular weight of from about 500 to about 1,500, and preferably about 1,000. Known toner resins, such as styrene methacrylates, styrene acrylates, styrene butadienes, and the like can also be added to the toner compositions of the present invention to assist in increasing toner elasticity. Moreover, the toner and developer compositions of the present invention enable the photoconductive imaging member present in an imaging apparatus to function for extended time periods, for example up to 75,000 cycles, while simultaneously preventing the localized accumulation of undesirable toner debris thereon which can encompass sufficient areas of the photoconductive members to permit unwanted toner spots to be present on the final developed output copy. Further, the developer compositions of the present invention possess stable electrical properties for extended time periods, and with these compositions, for example, there is no substantial change in the triboelectrical charging.
Developer and toner compositions with certain waxes therein are known. For example, there are disclosed in U.K. Patent Publication 1,442,835 toner compositions containing resin particles, and polyalkylene compounds, such as polyethylene and polypropylene of a molecular weight of from about 1,500 to 6,000, reference page 3, lines 97 to 119, which compositions prevent toner offsetting in electrostatic imaging processes. With the toners of the present invention, there is selected a polyethylene with a molecular weight of from about 500 to about 1,200 thereby enabling enhanced release of the developed image from the fuser roll. With the presence of the aforementioned wax in the toner no, or substantially no toner offset resulted for fuser silicone oiling rates as low as 2 microliters per copy, as contrasted, for example, from about 30 to about 50 microliters per copy needed to achieve toner image release in the absence of the polyethylene component. Additionally, the '835 publication discloses the addition of paraffin waxes together with, or without a metal salt of a fatty acid, reference page 2, lines 55 to 58. In addition, many patents disclose the use of metal salts of fatty acids for incorporation into toner compositions, such as U.S. Pat. No. 3,655,374. Also, it is known that the aforementioned toner compositions with metal salts of fatty acids can be selected for electrostatic imaging methods wherein blade cleaning of the photoreceptor is accomplished, reference Palmeriti et al. U.S. Pat. No. 3,635,704, issued Jan. 18, 1972, the disclosure of which is totally incorporated herein by reference. Additionally, there are illustrated in U.S. Pat. No. 3,983,045 three component developer compositions comprising toner particles, a friction reducing material, and a finely divided nonsmearable abrasive material, reference column 4, beginning at line 31. Examples of friction reducing materials include saturated or unsaturated, substituted or unsubstituted, fatty acids preferably of from 8 to 35 carbon atoms, or metal salts of such fatty acids; fatty alcohols corresponding to said acids; mono and polyhydric alcohol esters of said acids and corresponding amides; polyethylene glycols and methoxy-polyethylene glycols; terephthalic acids; and the like, reference column 7, lines 13 to 43.
Described in U.S. Pat. No. 4,367,275 are methods of preventing offsetting of electrostatic images of the toner composition to the fuser roll, which toner subsequently offsets to supporting substrates, such as papers, wherein there are selected toner compositions containing specific external lubricants including various waxes, see column 5, lines 32 to 45. Other references of interest which disclose the use of amides as toner additives include U.S. Pat. Nos. 4,072,521; 4,073,649 and 4,076,641. Furthermore, references of background interest are U.S. Pat. Nos. 3,165,420; 3,236,776; 4,145,300; 4,271,249; 4,556,624; 4,557,991 and 4,604,338.
Moreover, toner and developer compositions containing charge enhancing additives, especially additives which impart a positive charge to the toner resin, are well know. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of certain quaternary ammonium salts as charge control agents for electrostatic toner compositions. There are also described in U.S. Pat. No. 2,986,521 reversal developer compositions comprised of toner resin particles coated with finely divided colloidal silica. According to the disclosure of this patent, the development of images on negatively charged surfaces is accomplished by applying a developer composition having a positively charged triboelectric relationship with respect to the colloidal silica. Further, there are illustrated in U.S. Pat. No. 4,338,390, the disclosure of which is totally incorporated herein by reference, developer and toner compositions having incorporated therein as charge enhancing additives organic sulfate and sulfonate compositions; and in U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions containing resin particles and pigment particles, and as a charge enhancing additive alkyl pyridinium compounds, inclusive of cetyl pyridinium chloride. These and other charge additives can be incorporated into the toners of the present invention.
Other examples of prior art disclosing positively charged toner compositions with charge enhancing additives include U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014 and 4,394,430.